[PATCH -next] rust: poll: fix compilation error due to kvfree_call_rcu changes

kvfree_call_rcu() changed the type of its parameter to kvfree_rcu_head
in commit acc6fdade62c ("mm/slab: introduce struct kvfree_rcu_head for
kvfree_rcu batching") in the slab tree

Meanwhile rust started relying on the old type in commit e5e86df8b666
("rust: poll: use kfree_rcu() for PollCondVar") in the char-misc tree.

Reconcile the two changes as suggested by Gary [1]. This should be
applied as the merge commit for either slab tree or char-misc tree,
whichever is merged to -next later. The code it changes comes from
char-misc tree.

[1] https://lore.kernel.org/all/[email protected]/

Suggested-by: Gary Guo <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Vlastimil Babka (SUSE) <[email protected]>
---
 rust/kernel/sync/poll.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/sync/poll.rs b/rust/kernel/sync/poll.rs
index 684dfa242b1a..f3cdf95db12d 100644
--- a/rust/kernel/sync/poll.rs
+++ b/rust/kernel/sync/poll.rs
@@ -124,7 +124,7 @@ pub struct PollCondVarBox {
 struct PollCondVarBoxInner {
     #[pin]
     inner: PollCondVar,
-    rcu: Opaque<bindings::callback_head>,
+    rcu: Opaque<bindings::kvfree_rcu_head>,
 }
 
 // SAFETY: PollCondVar is Send

---
base-commit: 1701fda2f58e345c050f4309971bdc07cd6146ba
change-id: 20260805-slab-rust-fix-b1828ce329e3